The prior art of depilatory (hair-removal) devices includes variations of a well-known technique, namely, moving or rolling of a coil spring over the surface of the skin to pluck out hair which becomes trapped between the loops of the spring. An example of a moving spring design is described in U.S. Pat. No. 4,524,772 to Daar et al, in which a motor-powered spring moves in an endless loop and grabs hair between loops of the spring, providing a pulling action and removing the hair at its roots.
An example of a rolling spring design is described in Swiss patent 268,696 to Fischer, in which an arched spring is placed on the skin under slight pressure and moved against the direction of the hair growth, such that the spring rolls on the skin. It is specifically mentioned in the Fischer patent that the outside of the spring can be roughened by the provision of notches, thereby facilitating the rolling process on the skin.
The effectiveness of each of the prior art designs described above depends in large measure on the degree of certainty with which hairs falling between loops of the spring are grasped and eventually pulled out. Since the inner-facing coil spring surfaces are smooth, the possibility exists that hairs will slide out from between individual loops and not be removed.
Therefore, it would be desirable to provide a spring element for use in mechanical hair-removal devices which ensures a greater degree of effectiveness than that presently available.